Alternate action switch mechanism



July 24, 1962 D. WRIGHT 3,

ALTERNATE ACTION SWITCH MECHANISM Filed Jan. 15, 1962 QQHUBUUDUUT.

INVENTOR Duane WRIGHT BY W PATENT AGENT United States Patent Ofiice Patented July 24, 1962 3,045,591 ALTERNATE ACTION SWITCH MECHANHSM Duane Wright, North Dorval, Quebec, Canada, assignor to Burgess Micro Switch Co. Limited, Toronto, Ontario, Canada Filed Jan. 15, 1962, Ser. No. 166,019 4 Claims. (Cl. 74142) The present invention relates to an improved ratchet mechanism more particularly adapted to be used in conjunction with push button electric switches and the like so as to convert said switches into alternate action switches, or push on, push off switches.

The main object of the present invention resides in the provision of an alternate action switch mechanism incorporating a ratchet system of considerably improved life and efficiency mainly due to the absence of the leaf spring elements normally found in such mechanism and which have a tendency to brake down in use.

An important object of the present invention resides in the provision of a mechanism of the character described in which the pawl member is of rigid construction but is pivotally mounted such as to have freedom of movement towards and away from the ratchet wheel so that the pawl may clear the teeth of the ratchet wheel during its return movement.

Another important object of the present invention resides in the provision of a mechanism of the character described in which the springs are coil springs and act in compression so as to have a long life.

Yet another important object of the present invention resides in the provision of a mechanism of the character described in which the same coil springs are used for returning the pawl member into inactive position out of engagement with the ratchet wheel and for yieldably maintaining the lever designed to actuate the push button of the switch in contact with the cam member associated with the ratchet wheel.

Another important object of the present invention resides in a mechanism of the character described which is of simple and relatively inexpensive construction and which may operate one or several push button switches.

Yet another object of the present invention resides in the provision of a mechanism of the character described which is particularly designed for operating micro-switches and especially of the type used in control consoles for computers, aircraft cockpits, telephone switch boards, and the like and also of the type in which the actuating member is illuminated.

The foregoing and other important objects of the present invention will become more apparent during the following disclosure and by referring to the drawings, in which:

FIGURE 1 is a perspective view of a complete push on, push off switch assembly incorporating the mechanism of the present invention, said assembly being designed as an illuminated button switch for mounting in a display panel;

FIGURE 2 is a front elevation of the mechanism of the invention;

FIGURE 3 is a cross-section of the same showing the switch in off position; and

FIGURE 4 is a similar cross-section showing the switch in the on position, and the pawl member at the end of its active stroke.

Referring now more particularly to the drawings in which like reference characters indicate like elements throughout, the mechanism of the invention comprises a U-shaped sheet metal frame 1 which, in the embodiment illustrated, supports four micro-switches 2 of conventional construction and of the type having a spring pressed control button 3 which normally assumes a projecting position, as shown in FIGURE 3, and which retracts when depressed, as shown in FIGURE 4, the control button changing the condition of the switch internal circuit. The micro-switches 2 are secured side by side, with the interposition of insulating leaves 4, between the free end portions of the legs 5 of U-shaped frame 1, and the terminals 6 of the switches 2 project downwardly outwardly from the frame 1, while the control buttons 3 extend towards the bight 7 of frame 1.

A transverse shaft 8 is secured to the legs 5 of frame 1 and extends between the latter and rotatably supports a sleeve 9 preferably made of plastic such as nylon or the like which forms a central ratchet wheel 10 having inclined teeth 11 and on each side of wheel 10 two cam members 12, each of square shape; the ratchet wheel and cam member assembly is located between bight 7 and the micro-switches 2. A rigid sheet metal lever 13 is arranged between the micro-switches 2 and the ratchet wheel 10 and cam member assembly, said lever 13 having laterally projecting lugs 14 near one end thereof which enter slots 15 made in the legs 5- of frame 1, so as to constitute a pivotal connection for lever 13. The portion of lever 13 extending from lugs 14 to a point a little forward of the control button 3 of the micro-switches 2, extends the full width of the U-shaped frame 1 so as to be able to depress all four control buttons 3 simultaneously, while the portion forwardly of said last named portion constitutes two separate fingers 16, each adapted to extend opposite and contact the respective cam members 12. Each finger 16 is provided with a transverse groove 17 facing the associated cam member 12 so that the corner of said square shape cam members may engage said groove, as shown in FIGURE 4. The end of the lever 13 opposite fingers 16 is bent back upwardly and inwardly, as shown at 18, and said bent back portion 18 is provided with two spaced lugs 19.

A rigid pawl member 20, preferably made of sheetmetal, is pivotally mounted on frame 1 by means of a loose connection which permits movement of the pawl member towards and away from the ratchet wheel 10. More particularly, pawl member comprises a flat portion 21 extending the whole distance between the legs 5 of frame 1 and having along its rear edge laterally extending pivot lugs 22 which engage notches 23 made in the legs 5 along the back edges thereof. Additional locating lugs 24 laterally extend from the portion 21 at the front edge thereof and freely and loosely engage holes 25 made in the side legs 5 of frame 1. Portion 21 is extended centrally thereof with a downwardly bent tongue 26 opposite ratchet wheel 10 and engageable with the teeth 11 thereof. The line of action of tongue 26 on the teeth of the ratchet wheel is in a plane offset from the rotation axis of the ratchet wheel and located between said rotation axis and the pivot connection of the pawl member to the frame 1. Flat portion 21 of pawl member 20 is provided with two struck out lugs 27 which are downwardly and rearwardly inclined and are each inserted within the upper end of a coil spring 28, the lower end of which fits over lug 19 of lever 13. Preferably, there are two springs 28 and associated lugs 27 and 19 arranged on each side of the central tongue 26 and preferably on the outside of cam members 12. Springs 28 extend forwardly and upwardly towards pawl member 20 from their attachment to the lever 13. Springs 28 act under compression and exert a yielding force on lever 13 tending to pivot the same in a clockwise direction as seen in FIGURES 3 and 4 so as to maintain fingers 16 of lever 13 in yielding contact with the respective cam members 12 and, at the same time, coil springs 28 exert an upwardly and forwardly directed action on pawl member 20 so as to yieldably maintain the latter in a pivoted position out of engagement with the teeth 11 of wheel 11) and also maintain the pawl member in its limit forward position, that is with its pivot lugs 22 engaging the bottom of notches 23.

A plunger .29 is freely axially movable within a guiding bore made in a block 30 integral with and downwardly extending from a casing 31. The block 30 is screwed to the bight 7 of U-shaped frame '1 by means of screws 32 while plunger 29 passes through a central hole made in bight 7 and is provided with a head 33 in free contact with the top face of pawl member 20 at the front end of its fiat portion 21. The upper end of plunger 19 is connected to and supports a pusher member '34 closing the open end of casing 31 and preferably made of transluscent material so as to be illuminated from within by light bulbs disposed in casing 31 and fitted in sockets 35, said sockets being described and claimed in applicants copending patent application Serial No. 166,020 filed January 15, 1962 and entitled Socket for Electric Bulb. Casing 31 is provided with attachment members 36 for removably attaching the casing and switch assembly to a display panel and which are more fully described and claimed in applicants cO-pending patent application Serial No. 166,022 filed January 15, 1962 and entitled Mounting Means for Switches and the Like.

The mechanism in accordance with the present invention operates as follows:

When the pusher member 34 is released, coil springs 28 pivot pawl member 20 to its upper limit position out of engagement with the teeth of ratchet wheel 10 and pawl member in turn pushes on the head 33 of plunger 29, so that the latter takes its upper limit position defined by head 33 abutting against bight 7 of frame 1, as shown in FIGURE 3. Springs 28 also urge the lever 13 against cam members 12. In the position shown in FIG- URE 3, lever 13 abuts against the fiat edge faces of cam members 12 and therefore is in an upper pivoted limit position and control buttons 3 are in their released po sition, whereby microswitches 2 are in one electrical state for instance in their off position. Upon pressure exerted on pusher member 34, head 33 is depressed, which pivots pawl member 20 downwardly whereby its tongue 26 engages a tooth 11 of wheel 10 and causes rotation of said wheel through the distance of one tooth, that is, in the embodiment illustrated, a rotation of the wheel and cam member assembly through an angle of 45 whereby a corner of the cam members presses downwardly against the fingers 16 of lever 13 to depress the latter and the control buttons 3 of the micro-switches 2, whereby the latter take another electrical state, for instance, an on position. The lever 13 is pivoted downwardly against the action of coil springs 28. The cam members 12 and the lever 13 are maintained in engagement with each other due to the fact that the corner of the cam members engages groove 17 made in fingers 16.

Upon release of pusher member 34, coil springs 28 push the pawl member 20 and also plunger 29 and pusher member 34 upwardly into their upper limit position, but during this return movement of the pawl member, its tongue 26 must clear the next tooth 11 of ratchet wheel 10. This is permitted due to the free pivotal connection between the pawl member and frame 1, that is during this return movement, pawl member 20 moves transversely rearwardly against the action of the coil springs 28, more particularly lugs 22 move rearwardly out of engagement with the bottom of notches 23 as clearly shown in dotted line in FIGURE 4. Once the tongue 26 of pawl member 20 has cleared the ratchet tooth, the pawl member again moves forwardly due to the forward action of the coil springs 28 whereby the lugs 22 again engage the bottom of notches 23. Upon next depression of pusher member 34, the ratchet wheel and cam member assembly will again rotate through a 45 angle to thereby allow lever 13 to assume its upper limit position and again change the condition of themicro-switches 2 as shown in FIG- URE 3.

It will be noted that in the mechanism of the present invention, the lever 13 and the pawl member 20 are made of rigid material and that the only springs in the mechanism are the coil springs 28 which act in compression. Therefore, this mechanism has a very long life as compared to ratchet mechanism employing leaf blades as springs.

The holes 25 have a larger size than the width of location lugs 24, so as to permit free movement of the pawl member with respect to frame 1, *while preventing lugs 22 from disengaging notches 23.

The mechanism of the present invention may also be used for operating other devices than switches.

While a preferred embodiment in accordance with the present invention has been illustrated and described, it is understood that various modifications may be resorted to without departing from the spirit and scope of the appended claims.

What 1 claim is:

1. A ratchet mechanism comprising a frame, a toothed ratchet wheel rotatably mounted in said frame, a rigid pawl member having a ratchet wheel engaging end laterally offset from the rotation axis of said ratchet wheel, said pawl member loosely pivotally supported on said frame at its other end for transverse movement relative to said frame and ratchet wheel between a normal position and a laterally displaced position, spring means exerting a yielding force on said pawl member along an inclined direction to urge said pawl member into a pivoted position out of engagement with said ratchet wheel and into said normal lateral position, and manually operated actuator means engageable with said pawl member between the two ends of the latter to cause the latter to engage said ratchet wheel against the action of said spring means and rotate said ratchet wheel the distance of one tooth, said spring means returning said pawl member to its pivoted position out of engagement with said ratchet wheel and into said normal position upon release of said actuator means, disengagement of said pawl member with the teeth of said ratchet wheel during return movement of said pawl member being permitted by the transverse movement of said pawl member to temporarily assume its laterally displaced position against the action of said spring means.

2. A ratchet mechanism as claimed in claim 1, wherein said manually operated actuator means consist of a plunger member freely axially movably mounted in said frame.

3. A ratchet mechanism as claimed in claim 1, further including a cam member rigid with and coaxial with said ratchet wheel, a lever pivotally mounted intermediate its ends on said frame, and having one end portion engageable with said cam member, and the other end attached to said spring means, said spring means consisting of at least one compression coil spring urging said lever to engage said cam member at the same time it exerts its force on said pawl member, rotation of said cam member causing oscillating pivotal movement of said lever.

4. In combination with an electric switch having a spring pressed axially movable control button, a frame to which said switch is secured, a lever pivotally mounted intermediate its ends on said frame and engageable with said button, a combined toothed ratchet wheel and cam member rotatably mounted in said frame with said cam member in engagement with one end portion of said lever, a rigid pawl member having a ratchet wheel engaging end laterally offset from the rotation axis of said ratchet wheel and cam member and loosely pivotally supported on said frame at its other end for pivotal movement and also transverse movement relative to said frame, a coil spring engaging at one end an intermediate portion of said pawl member and at the other end the other end portion of said lever and simultaneously exerting a yielding force on said pawl member to cause the same to assume a pivoted position out of engagement with said ratchet wheel, and a force on said lever to cause its first named end to yieldably engage said cam member, and manually operated actuator means slidably and freely mounted in said frame and engageable with said pawl member whereby axial movement of said actuator means towards said pawl member will cause the latter to pivot and engage said ratchet wheel against the action of said spring means and rotate said ratchet wheel, the distance of one tooth, said cam member in turn causing pivotal movement of said lever against the action of said spring, said spring returning said pawl member to its original position out of engagement with said ratchet wheel upon release of said actuator means, disengagement of said pawl member with a teeth of said ratchet wheel during return movement or" said pawl member being permitted with the transverse movement of said pawl relative to said frame, said cam member causing depression of said button through said lever at each alternate depression of said actuator means and allowing outward movement of said button at each intermediate depression of said actuator means.

References Cited in the file of this patent UNITED STATES PATENTS 2,820,113 Lewis et a1. Jan. 14, 1958 2,990,723 Holpuch July 4, 1961 

